Hesitate to enter the hornets' nest, but as I understand it, htere are four options for when you leave your machine for a while
* On
* Sleep
* Hibernate
* Off
Leaving the machine on uses a lot of power, and the screens can be set to remain on, or to switch off after a while. This is useful if you want to run a background program like bitcoin mining, or SETI or other computer resource-sharing program.
Sleep mode will keep everything running, and might wake up at regular intervals to check emails, or when there is a contact request from elsewhere on the network. If none of these hings happen, the disk and the display will switch off after a pre-determined period.
Hibernate is a more extreme form of sleep, in that the machine saves a lot of state data to the disk, and then more or less switches off. Disk off; screen off; processor off; networking off. When you wake it, the disk spins up, and then restores the saved data (which programs are running, open windows, memory allocations etc).
In the off mode, then everything is off. IN order to restart, it has to load the OS, and all the separate programs and so on.
The machine will probably carry out Windows updates in On and Sleep mode, but not in Hibernate or Off modes.
There was an argument a few years ago that the thermal and physical shock of starting a disk and stopping it a couple of times a day was more damaging than running the disk permanently. I think that has more or less gone away now, so there is a recommendation to minimise power consumption, and the components will survive the various shocks.
I have a couple of Mac laptops. My main machine is switched off every evening, and on again in the morning.
My ultra-portable remains on all the time, but goes to sleep whenever I close the lid.
One of the factors in my decision on whether to switch off/sleep is that I have all SSD drives. These vastly speed up the time from power-on to making the machine available for use.
On a mechanical spinning disk, that can take 5 minutes. On my SSD machines, it is usually less than a minute.
If there is a single upgrade I'd recommend for the impatient computer user, its an SSD drive. You can get a 500MB drive for around GBP100 nowadays
As to managing Windows updates - the Macs allow you to control when those are installed. I think I'd probably use the 'metered connection' setting on Windows to give me back control of when to install various updates.
Personally, I would discount the hacking issue. If you have the right software, you will see that there are many probes, testing the security of your machine each hour. If your defences are weak, you'll probably be hacked while on chatting AB. If they are strong, then you can leave it on all night with no real increase in risk.
Absolutely, you should never remain logged in to sensitive sites unless you are actively using the connection. Personally, I always log out of every vaguely sensitive website that I am not actively using (including AB).